Resolve TODO: human-readable image-suffixes

This conditional was required temporarily so containers#247 could merge.  Remove
and replace it with a version that avoids modifying any files and only
checks if `IMG_SFX` changes were made.

Signed-off-by: Chris Evich <[email protected]>

ci/validate.sh

@@ -33,19 +33,17 @@ if ! git diff --name-only ${CIRRUS_BASE_SHA}..HEAD | grep -q IMG_SFX; then
 Simply run 'make IMG_SFX', commit the result, and re-push."
 fi
 
-# Verify new IMG_SFX value always sorts later than previous value.  This prevents
-# screwups due to local timezone, bad, or unset clocks, etc.
-cd $REPO_DIRPATH
-# Automation requires the date and time components sort properly
-# as if they were version-numbers regardless of distro-version component.
-new_img_ver=$(awk -F '-' '{print $1"."$2}' ./IMG_SFX)
-# TODO: Conditional checkout not needed after the PR which added IMG_SFX file.
-if git checkout ${CIRRUS_BASE_SHA} IMG_SFX; then
-  old_img_ver=$(awk -F '-' '{print $1"."$2}' ./IMG_SFX)
+# If IMG_SFX was modified vs PR's base-branch, validate the changes.
+v_prev=$(git show ${CIRRUS_BASE_SHA}:IMG_SFX 2>&1 || true)
+if ! [[ $v_prev =~ "exists on disk, but not in" ]]; then
+  # Verify new IMG_SFX value always sorts later than previous value.  This prevents
+  # screwups due to local timezone, bad, or unset clocks, etc.
+  new_img_ver=$(awk -F 't' '{print $1"."$2}' ./IMG_SFX | cut -dz -f1)
+  old_img_ver=$(awk -F 't' '{print $1"."$2}'<<<"$v_prev" | cut -dz -f1)
+  # Version-sorting of date/time mimics the way renovate will compare values
+  # see https://github.com/containers/automation/blob/main/renovate/defaults.json5
   latest_img_ver=$(echo -e "$old_img_ver\n$new_img_ver" | sort -V | tail -1)
   [[ "$latest_img_ver" == "$new_img_ver" ]] || \
-    die "Date/time stamp appears to have gone backwards! Please commit
-an 'IMG_SFX' change with a value later than '$(<IMG_SFX)'"
-else
-  warn "Could not find previous version of IMG_SFX, ignoring."
+    die "Updated IMG_SFX '$(<IMG_SFX)' appears to have gone backwards! Please commit
+an 'IMG_SFX' change with a value later than '$(v_prev)'"
 fi